Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gearbox torque calculation - input/output

  1. Aug 25, 2012 #1
    Hi all,

    Please help me to solve this fairly simple problem (i think):

    Gearbox output torque driving the input shaft to pump = 0.12348 Nm
    Gearbox output speed - 80 rpm
    Gearbox input speed - 4 rpm

    Gearbox is compound consisting of x4 gears arranged in two pairs -

    Gear A, driver = 100 teeth
    Gear B, driven = 20 teeth
    Gear C, driver = 80 teeth
    Gear D, driven = 20 teeth

    Gearbox Ratio = 1:20

    How do I calculate the input torque?

    Thanks in advance
  2. jcsd
  3. Aug 25, 2012 #2
    It seems to me your gearbox is working from low speed to high speed, meaning your gear ratio is speeding up the rotation, which means it is reducing the torque by the same ratio.

    take your 'output' torque and multiply this by the ratio to get the input torque.

    What's your application? This is opposite of how I use gearboxes.
  4. Aug 26, 2012 #3
    Hi Huntoon,

    The question is related to a concept design where a power spring will be driving the input to a pump; think along the lines of the Baylis wind-up radio.

    And thanks for your response, i was hoping it was that simple.
  5. Aug 26, 2012 #4
    double check your math and my logic. you get what you pay for, you know what I mean.... happy to help though, cheers.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook